Acquired Ichthyosis

A 17-year-old male with Crohn disease presented with a history of abdominal pain for 2 days and a diffuse, scaly rash for 2 weeks. Physical examination revealed lower abdominal tenderness and right hip pain with flexion. Coarse skin with hyperpigmented, rectangular lesions in horizontal arrays was distributed over his trunk, buttocks, and lower extremities (A).

Computed tomography scans of the abdomen and pelvis showed an iliopsoas abscess (B), which was drained percutaneously. Gastrointestinal and cutaneous manifestations resolved 2 months after initiation of infliximab therapy.

Acquired ichthyosis (AI) is characterized by symmetric, dry skin with platelike scales distributed over the trunk and limbs.¹ The condition is asymptomatic other than mild pruritus and is more prominent over the lower extremities.² On histologic examination, hyperkeratosis and the lack of a granular layer are seen.³ AI is associated with autoimmune disease, hypothyroidism, malignancy, sarcoidosis, liver disease, chronic kidney disease, nutritional deficiency, AIDS, and inflammatory bowel disease.^4,5 AI has also been associated with medications such as cimetidine and cholesterol-lowering agents.⁴

AI should be differentiated from ichthyosis vulgaris, an autosomal dominant form of ichthyosis with onset before the age of 13 years. Ichthyosis vulgaris is the most common form of ichthyosis, occurring in 1 of 250 individuals.⁶ The onset of ichthyosis after the age of 13 years, especially in patients without a family history of the condition, should raise suspicion for a secondary cause.

AI resolves with treatment or removal of the underlying cause.⁴ Symptomatic treatment of AI includes hydration, lubricants, and keratolytic agents.⁴ Hydration is accomplished with lactic, glycolic, or pyruvic acids. Petrolatum should be applied after showering. Keratolytic agents such as salicylic acid, urea, propylene glycol, and lactic acid are useful for removal of scales.